Glass Heating Furnance with Opposing Gas Streams

ABSTRACT

The invention disclose a convection glass heating furnace, which includes upper and lower furnace bodies, at least one gas-collection box are set in the upper and lower furnace bodies respectively, glass inlets and outlets are setup in the gas-collection box, and a jet-flow plate is set at the gas outlets. The gas inlets of gas-collection box are connected with the exhaust port of a blower fan through pipelines. Gas heating devices are setup in the gas-collection boxes. The gas inlets of the blower fan and its upstream gas routes along with the exhaust port of the blower fan and its downstream gas route form a gas circulation loop together. Glass is heated in the heating furnace of the invention by the hot gas sprayed on its surfaces, so the deficiencies of low heating efficiency and long heating time can be effectively avoided when heating the glass with high reflectivity and transmission ratio. The power of the heating devices can be expediently selected according to the temperature and the flow rate of the hot gas needed, in particular, the hot gas sprayed on the upper and under surfaces of the glass can be set to different temperatures to make the upper and under surfaces of the glass be heated uniformly and ensure the heating quality.

TECHNOLOGICAL SCOPES

This invention relates to a glass heating furnace, especially a heatingfurnace used to heat glass with complete convection method.

BACKGROUND OF THE INVENTION

The existing glass heating furnaces are working with radiation mode,i.e. heating glass with infrared rays emitted from resistance heatingelements. Because of smaller blackness of some kinds of glass, thereflectivity and transmission ratio are higher, it is not good forabsorbing radiation heat, and therefore, heating with normal radiationmode has a problems of longer heating time and lower heating efficiency.For example, in case of LOW-E, great deal of heat is reflected, thetemperature on the surface of glass cannot meet requirements. Inaddition, when heating with radiation, roller-table transfers heatdirect to the lower surface of glass. This part of conductive heat islarger than the radiation heat received on upper surface of glass, whichleads to some certain temperature difference between upper and lowersurfaces of the glass, causing warping at the edges of glass, and whitefog occurs at the part contacting with the roller-table, and finallyaffecting the processing quality of glass.

SUMARY OF THE INVENTION

Aiming to the deficiency of the existing technology, the purpose of thisinvention is to provide a convection glass heating furnace. A jet-flowheating technology is used in this furnace. High temperature gas isblown onto the glass surface. Heating is completed with help ofconvection heat-exchange between high temperature gas and glass.

In order to reach the above goal, this invention—convection glassheating furnace includes upper and lower furnace bodies, at both sidesof which, a glass inlet and an outlet are set respectively, a glasstransportation roller-table is installed in the lower furnace body, atleast one gas-collection box is set inside the upper furnace and thelower furnace respectively. This gas-collection box is a sealed box onwhich are set at least a gas inlet and a gas outlet, at the gas outletis set a jet-flow plate; high temperature gas ejecting holes are set onthe jet-flow plate. The gas outlet of the gas-collection box is facingthe glass transportation roller-table, and has a certain distance to theglass transportation roller-table. The gas inlet of the gas-collectionbox is connected with the exhaust port of the fan through a pipe. Gasheating devices are set at the gas passage composed of exhaust port ofthe fan, pipes, gas-collection box, and the high-temperature gas jettingport on the jet-flow plate of gas-collection box. At least an exhaustport is set on the upper and lower furnace bodies respectively. Gasinlet of the fan connects with the exhaust ports of the upper and lowerfurnace bodies through pipes. A gas circulation loop is composed of theinlet of the fan and its upstream gas route and the exhaust port of thefan and its downstream gas route.

In addition, the mentioned gas-collection boxes in the upper and lowerfurnace bodies are connected with its own fan. An independent gascirculation loop is formed respectively.

In addition, exhaust gas recovery holes are set on the mentionedjet-flow plate, the exhaust gas recovery holes are connected with theinner cavity of the furnace body outside of the gas-collection box viapipes.

In addition, the mentioned jet-flow plate is in shape of wave, and thementioned high-temperature gas ejecting holes are distributed near thewave though of the roller-table on the mentioned lower furnace body. Theexhaust gas recovery holes are set at the wave crest of the roller-tablefar from the mentioned lower furnace body.

In addition, the mentioned gas heating device is an electric heatingelement which is set inside of the gas collection box.

In addition, the mentioned heating element is a clip-port heater, whichis composed of insulated porcelain and resistance wires or resistancetapes. There are several opening troughs around the insulated porcelain.A column is formed with numbers of overlaid insulated porcelains.Resistance wires or resistance tapes wind around the column in spiralform via the opening trough on the insulated porcelain. The two polesare lead out through the installation flange at one end of the column.

In addition, the mentioned gas-collection box in the upper furnace bodycan be installed on the furnace body and can be moved up and down by asuspension mechanism.

In addition, the mentioned suspension mechanism is a mechanism composedof screws and nuts, the gas-collection box is hung on the screws vianuts, and the screws are fixed on the upper furnace body, the top ofwhich is connected with the control mechanism which set on the top partof wall of the furnace body. The control mechanism is a worm and gearcontrol mechanism, or gears or chain wheels control mechanism.

In addition, the gas-collection box in the mentioned lower furnace bodyis supported on a lifting and lowing device which is installed on thelower furnace body and can move up and down.

The mentioned lifting and lowing mechanism is a lifting and lowingmechanism composed of screws and nuts, the mentioned gas collection boxis fixed with nuts, and connected with the screws via nuts. The screwthat can rotate is installed on the lower furnace body. Said screw isconnected with the control mechanism of worm and gear, or with the gearor chain wheel control mechanism, and can rotate under control of thecontrol mechanism.

This invention of the furnace uses the method of ejectinghigh-temperature gas onto the surface of glass to heat the glass. Thateliminates the defects of lower heating efficiency and longer heatingtime during heating glass with higher heating reflectivity and highertransparency by using the traditional furnaces. After the heatingelement is set inside the gas-collection box, the power of the heatingelement can be selected easily according to the required temperature andflow of the high-temperature gas, especially, the high-temperature gasejecting on the upper and lower surfaces of the glass can be set todifferent temperature, therefore, the upper and lower surfaces of theglass is heated evenly, which ensures the heating quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of this invention;

FIG. 2 is E-E view of FIG. 1;

FIG. 3 is a schematic diagram of the structure of the jet-flow plate;

FIG. 4 is F-F view of FIG. 3;

FIG. 5 is a schematic diagram of the structure of the insulationporcelain;

FIG. 6 is G-G view of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 and 2, convection glass heating furnace according tothe invention includes lower furnace body 1, upper furnace body 5; glassinlet 3 and glass outlet 10 are set on both side of the upper and lowerfurnace bodies. Glass transporting roller-table 12 is installed on lowerfurnace body 1. Twelve gas-collection boxes 2 are set inside the upperand lower furnace bodies respectively. The gas-collection box 2 is asealed box on which are set gas inlet 4 and gas outlet. At the gasoutlet is set a jet-flow plate 18 on which are set a lot ofhigh-temperature gas ejecting ports 16 and exhaust gas recovery holes 17(see FIGS. 3 and 4). The gas outlet of the gas-collection box 2 isfacing the glass transportation roller-table 12, and has a certaindistance to the glass transportation roller-table 12. The gas inlet 4 ofthe gas-collection box 2 is connected with the exhaust port of the fan 8by pipe 6. Clip-port electric heater 9 is set in each gas-collection box2. The gas inlet of fan 8 inhales exhaust gas at exhaust gas recoveryhole 17 on the jet-flow plate of the gas-collection box through pipe 7and pipe 19 inside gas-collection box 2. Pipe 19 inside gas-collectionbox 2 leads the exhaust gas at exhaust gas recovery hole 17 into theinside cavity of the furnace body at the end of gas-collection box 2which is far from the transportion roller-table. Gas inlet of fan 8,pipe 7, inner cavity of the furnace body, pipe 19 inside gas-collectionbox 2, exhaust gas recovery hole 17, exhaust port of fan 8, pipe 6,gas-collection box 2 and high-temperature gas ejecting hole 16altogether form a gas circulation loop. A clip electric heater 9 isinstalled in each gas-collection box 2. This clip electric heater 9 islocated on the gas passage between high-temperature gas ejecting hole 16and gas inlet of gas-collection box 2. Gas-collection box 2 in the upperfurnace body 5 is in section view state. Each gas-collection box 2 inthe upper furnace body 5 is hung on two screws 20 via nuts 22. Screw 20that can rotate is fixed on the top wall of the upper furnace body. Thetop of screw 20 is connected with the control mechanism 21 composed ofworm and gear. Under control of control mechanism 21, screw 20 rotatesand makes gas-collection box 2 move up and down. Each gas-collection box2 in lower furnace body 1 is supported on two or four screws 24 via nuts23 respectively. The lower end of screw 24 can be installed rotately onthe lower furnace body 1. The lower end of screw 24 is connected withcontrol mechanism 25 composed of worm and gear. Under control ofmechanism 25, each screw 24 rotates and makes gas-collection box 2 thatis connected with it move up and down.

Shown as in FIGS. 3 and 4, the cross section of jet-flow plate 18 at thegas outlet of gas-collection box 2 is in wave form. Each gas ejectinghole 16 is set at the wave trough. Each square exhaust gas-recovery hole17 is set at the wave crest. In gas-collection box 2, saidhigh-temperature gas ejecting hole 16 is close to glass transportationroller-table 12. Exhaust gas recovery hole 17 is far away from glasstransportation roller-table 12. Pipe 19 connects exhaust gas recoveryhole 17 with the inner cavity of the furnace body, but is isolated fromthe inner cavity of gas-collection box 2. The wave type of cross sectionof jet-flow plate 18 can be even wave shape or uneven wave shape inwhich the locations of each wave crest and wave trough are incongruous.Because jet-flow plate 18 of gas-collection box 2 in upper furnace body5 directly faces the glass to be heated, while jet-flow plate 18 ofgas-collection box 2 in lower furnace body 1 is separated from the lowersurface of glass by the glass transportation roller-table, therefore,the form of the jet-flow plate of gas-collection box 2 in the upper andlower furnace bodies can be made in different shapes in order to makethe upper and lower surfaces of the glass to be heated evenly. Eachgas-collection box and jet-flow plate in upper furnace body 5 or lowerfurnace body 1 also can be made in different shapes in order to makeglass to be heated evenly in each part of upper furnace body 5 and lowerfurnace body 1.

What is shown in FIGS. 5 and 6 is a schematic diagram of the structureof insulated porcelain. Clip electric heater 9 is composed of severalinsulated porcelains and resistance-tapes, said insulated porcelains areoverlaid into a column, and said resistance tapes wind around the columnin spiral form via the opening trough 15 on the insulated porcelain. Theinsulated porcelain column is supported on the side wall ofgas-collection box 2. Both ends of the resistance tape are lead outthrough the installation flange set at one end of the insulatedporcelain, wherein one pole is connected with a metal connection rodthat runs thought the hole 14 inside the insulated porcelain.

When the invented device is working, glass 11 to be heated enters thefurnace body through glass inlet 3 from one side of the furnace body andis supported on glass transportation roller-table 12. Fan 8 send gasalong arrow C in FIG. 1 into each gas-collection box 2. Gas that enteredgas-collection box 2 turns into high temperature gas with the help ofheater 9. The heated high-temperature gas is ejected onto the upper andlower surfaces of glass through high-temperature gas ejecting hole 16 onjet-flow plate 18. The exhaust gas after convection and heat exchangingwith glass to be heated enters the inner furnace cavity that is far fromthe glass through exhaust gas recovery hole 17 and pipe 19. The exhaustgas is sucked in fan 8 through holes set in the furnace body, then, fan8 send the sucked exhaust gas to gas-collection box 2 again to makeanother circulation; it circulates again and again like this.

After gas-collection box 2 that can move up and down is installed in theupper and lower furnace bodies, it is not only convenient for repair andmaintenance of gas-collection box 2, but also convenient for change andmaintenance of the heater inside gas-collection box 2.

Glass surfaces to be heated can be covered with numbers ofgas-collection boxes 2 which are set inside the upper and lower furnacebodies respectively. In this way, it is not only convenient for process,installation and maintenance of gas-collection box 2, but also moreconvenient for distribution of heating power at each part of the furnacebody, and favorable for control of glass-heating state. Becausegas-collection box 2 is set in upper furnace body 5 and lower furnacebody1 respectively, and each gas-collection box 2 is correspondinglyindependent, so, quantity of gas-collection boxes and position of eachgas-collection box can be set pertinently according to the actualsituation of the upper and lower surfaces of heated glass.Gas-collection boxes in the upper and lower furnace bodies can be setsymmetrically or not. The heating power of the heater in eachgas-collection box can be the same, and can be different. The volume andstructure of each gas-collection box can be completely the same, andalso can has different structure and size.

1. A kind of convection glass heating furnace, wherein it includes upperand lower furnace bodies, glass inlet and outlet that set beside theupper and lower furnace bodies respectively, a glass transportationroller-table installed in the lower furnace body, at least onegas-collection box set in the upper and lower furnace bodiesrespectively, said gas-collection box is a sealed box on which are setat least a gas inlet and a gas outlet at which is set a jet-flow plate,high temperature gas ejecting holes and exhaust gas recovery holes areset on the jet-flow plate, said gas outlet of the gas-collection box isfacing the glass transportation roller-table, and has a certain distanceto the roller-table, said gas inlet of the gas-collection box isconnected with the exhaust port of the fan through a pipe, gas heatingdevices are set at the gas passage composed of exhaust port of the fan,pipes, gas-collection boxes, and the high-temperature gas jetting portson the jet-flow plate of gas-collection box, exhaust ports are set onthe upper and lower furnace bodies respectively, gas inlet of the fanconnects with the exhaust ports of the upper and lower furnace bodiesthrough pipes, a gas circulation loop is composed of the inlet of thefan and its upstream gas route and the exhaust port of the fan and itsdownstream gas route.
 2. The convection glass heating furnace accordingto claim 1, wherein the gas-collection boxes in the upper and lowerfurnace bodies are connected with each fan respectively, and independentgas circulation loop is formed respectively.
 3. The convection glassheating furnace according to claim 2, wherein exhaust gas recovery holesare set on the mentioned jet-flow plate; the exhaust gas recovery holeis connected with the inner cavity of the furnace body outside of thegas-collection box by a pipe.
 4. The convection glass heating furnaceaccording to claim 3, wherein the mentioned jet-flow plate is in shapeof wave, and the mentioned high-temperature gas ejecting holes aredistributed on the wave though near the roller-table on the mentionedlower furnace body, said exhaust gas recovery holes are set at the wavecrest far from the roller-table of the mentioned lower furnace body. 5.The convection glass heating furnace according to claim 4, wherein thementioned gas heating device is an electric heating element that is setinside the gas-collection box.
 6. The convection glass heating furnaceaccording to claim 5, wherein the mentioned electric-heating element isa clip heater, said heater is composed of insulated porcelain, andresistance wires or resistance tapes, numbers of opening troughs aremade around the insulated porcelain, a column is formed with numbers ofoverlaid insulated porcelains, resistance wires or resistance tapes windaround the column in spiral form via the opening trough on the insulatedporcelain, two poles are lead out through the installation flange at oneend of the column.
 7. The convection glass heating furnace according toclaim 6, wherein the gas-collection box in the mentioned upper furnacebody can be installed in the upper furnace body and can be moved up anddown by a suspension mechanism.
 8. The convection glass heating furnaceaccording to claim 7, wherein the mentioned suspension mechanism is amechanism composed of screws and nuts, the gas-collection box is hung onthe screws via nuts, and the screws are fixed on the upper furnace body,the upper end of which protruding out of the top wall is connected witha control mechanism of worm and gear or a control mechanism composed ofgears or chain wheels.
 9. The convection glass heating furnace accordingto claim 8, wherein the gas-collection box in the mentioned lowerfurnace body is supported on a lifting and lowing device which isinstalled in the lower furnace body and can move up and down.
 10. Theconvection glass heating furnace according to claim 9, wherein thementioned lifting and lowing mechanism is a screw-and-nut lifting andlowing mechanism, said gas-collection box is fixed with the nuts andconnected with the screws by the nuts. Each screw that can rotate isinstalled in the lower furnace body, said screw is connected with themechanism of worm and gear or gear or chain wheel, and can rotate undercontrol of the control mechanism.